The dispute over payment to teachers for supervision cover - which could see further disruption of schools this year - is still unresolved after new talks failed to break the deadlock.
Last night one source said the talks were now "in crisis". Schools face further disruption unless the issue is resolved before the October 1st deadline.
Talks between the Department of Education, the teaching unions and school managers were suspended last night without agreement. A fresh attempt to break the deadlock will be made on Friday.
Yesterday's meeting was attended by the ASTI. The union had been refusing to join other teaching unions at the talks until its 30 per cent pay claim was resolved. But two months ago, it changed policy and agreed to "contacts" with the Department on the issue.
Discussions between the TUI, the INTO, school managers and the Department have been continuing since April.
Most teachers perform supervision and provide substitution cover for absent colleagues on a voluntary, unpaid basis.
In its findings on the ASTI dispute earlier this year, the Labour Court said this ad hoc system should be regularised.
The teaching unions want an allowance of about £2,000 per annum for supervision and substitution cover. They would also like to see this allowance regarded as a pensionable payment. The ASTI has warned of possible further school disruption if the issue is not resolved.
Yesterday, on the margin of the talks, the Department made what sources said was an "improved" offer but there is still some distance between the sides.
Ideally, the Department would like to pay an hourly rate to teachers for supervising pupils during break times but the unions favour an annual allowance. They also want to be paid at overtime rates.
Teachers also want the allowance for covering as substitutes in the classroom. These would be paid when teachers take a class where the original teacher is absent because of "uncertified sick leave or other approved absences".
The Department, however, believes school managers should be free to hire non-teachers - such as parents - for supervision if teachers refuse to co-operate with the new system.
The current talks on supervision were set up after the Labour Court issued a recommendation during the ASTI dispute, saying it was an area worth examining.